<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <script>
        var a = prompt("请输入年份");
        if(a%4==0){
            alert("闰年")
        }
        else if(a%4==1){
            alert("平年")
        }
        else if(a%4==2){
            alert("平年")
        }
        else if(a%4==3){
            alert("平年")
        }
        else if(a%4==4){
            alert("平年")
        }
    </script>
</body>
</html>